Summary - Loops

Combine for, while and for-each to write a multiplication table.

Summary - Loops

In this group you learned loop structures:

for: counting loop
while: conditional loop
do-while: at least once
break/continue: loop control
for-each: walks an array without an index

These structures let you write repeated work in short code. Now combine them and write a multiplication table.

Exercise Multiplication table (2)

Write a Main class with a main method. Write for (int i = 1; i <= 5; i++). Each turn print System.out.println(2 * i). This makes the first 5 rows of the 2 times table.

Show example solution

public class Main {
    public static void main(String[] args) {
        for (int i = 1; i <= 5; i++) {
            System.out.println(2 * i);
        }
    }
}

Exercise Array sum (for-each)

Write a Main class with a main method. Assign {2, 4, 6} to int[] nums. Assign 0 to int sum. With for (int n : nums) do sum += n. Finally print System.out.println(sum).

Show example solution

public class Main {
    public static void main(String[] args) {
        int[] nums = {2, 4, 6};
        int sum = 0;
        for (int n : nums) {
            sum += n;
        }
        System.out.println(sum);
    }
}

Test yourself

Which loop runs the body at least once?
- for-each
- for
- while
- do-while
Show answer

do-while — do-while runs the body first, then tests the condition.
Match the loop structures

for

Counting
while

Condition
do-while

At least 1
for-each

No index

Complete the for-each

int[] nums = {1, 2, 3};
for (int n : ____) {
    System.out.println(n);
}

Show answer

int[] nums = {1, 2, 3};
for (int n : nums) {
    System.out.println(n);
}

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